Siemens SIMATIC S5-100U System Manual page 155

S5-100U
You can use the "LC" operation to convert a binary number to a BCD number for timers and
counters.
Example: Comparing a count in counter 1 with decimal number 499
The comparison value must be stored in the accunulator by means of a load
operation. Use the "LKF + 499" statement so that you do not have to convert the
value 499 into other numerical systems (binary or hexadecimal) for the input. The
number 1F3
The current count must also be loaded into the accumulator.
Incorrect Method:
If you use the "LCC1"
statement, the current count will
be loaded in BCD. The "!=F"
comparison operation results in
a "not equal to" condition since
the comparison uses different
formats.
0 0 0 0 0 0 0 1 1 1 1 1 0 0 1 1
0 0 0 0 0 1 0 0 1 0 0 1 1 0 0 1
EWA 4NEB 812 6120-02b
is then stored in the accumulator.
H
L KF+499
LC C 1
Introduction to STEP 5
Correct Method:
The formats are identical if the
"LC1" statement is input.
High Byte Low Byte
0 0 0 0 0 0 0 1 1 1 1 1 0 0 1 1
L KF+499
0 0 0 0 0 0 0 1 1 1 1 1 0 0 1 1
L C 1
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